Process and welding rod for the welding of ductile cast iron

ABSTRACT

A process for the electric arc welding of cast iron, specifically ductile cast iron, is provided which comprises electrically applying to the cast iron to be welded, at welding temperatures, a welding material obtained by simultaneously melting a first and a second welding rod; the first welding rod containing, by weight, about 0.085 to about 0.095 percent carbon, about 0.0285 to about 0.0315 percent chromium, about 0.0095 to about 0.0105 percent nickel, about 0.0095 to about 0.0105 percent molybdenum, about 0.618 to about 0.672 percent manganese, about 0.01615 to about 0.01785 percent sulphur, about 0.01805 to about 0.01995 percent phosphorus, about 2.50 percent silicon, with the balance being iron plus incidental impurities, the first welding rod being provided with a low hydrogen fluxing material; the second welding rod containing, by weight, about 2.85 percent carbon, about 0.01 percent chromium, about 0.10 percent nickel, about 0.05 percent molybdenum, about 0.50 percent manganese, about 0.08 percent sulphur, about 0.50 percent phosphorus, about 2.50 percent silicon, with the balance being iron plus incidental impurities.

BACKGROUND OF THE INVENTION

The present invention relates to the welding of cast iron at ambienttemperatures without the application of additional heat.

It is customary in the art to hot weld cast iron. In those processes,the cast iron structure which is to be welded is first heated by anexternal or supplemental means and then the welding material is appliedthereto. Obviously, there are certain drawbacks or limitationsassociated with the implementation of such a hot welding process whichare to be avoided or at least minimized, if at all possible. Forexample, it is often impossible to hot weld assembled cast ironstructures which are placed in confined areas having limited access.

Accordingly, it is the primary objective of this invention to provide ameans for welding cast iron, especially ductile cast iron, at ambienttemperatures without the application of supplemental heat.

In addition, it is a further object of the invention to provide variouselectrode structures which are especially suited for use in the processof the instant invention.

These and other objects of the invention will be obvious to thoseskilled in the art from a reading of the following specification andclaims.

RELATED APPLICATIONS

On even date herewith, the inventor of the innovation described hereinhas also filed certain other applications which relate to the welding ofvarious forms of cast iron. These applications are as follows: U.S.patent application Ser. No. 612,666 filed Sept. 12, 1975 for "A Processand Welding Rod for Welding Gray Cast Iron"; U.S. patent applicationSer. No. 612,667, filed Sept. 12, 1975 entitled "A Process and WeldingRod for the Welding of White Cast Iron"; U.S. patent application Ser.No. 612,674, filed Sept. 12, 1975 entitled "A Process and Welding Rodfor the Welding of Malleable Cast Iron"; and U.S. patent applicationSer. No. 612,665, filed Sept. 12, 1975 entitled "Process and CoatedWelding Rod for Welding White Cast Iron".

SUMMARY OF THE INVENTION

Broadly stated the instant invention concerns a novel process for theelectric arc welding of cast iron of the type generally referred to asductile iron without the application of supplemental heat. Basically,this is accomplished by depositing a weld on the article to be welded bysimultaneously melting two unique welding rods.

More specifically the present invention relates to a process for theelectric arc welding of cast iron containing, by weight, about 3.0 toabout 4.0 percent carbon, about 1.8 to about 2.8 percent silicon, about0.10 to about 1.0 percent manganese, about 0.00 to about 0.03 percentsulphur, about 0.00 to about 0.10 percent phosphorus, with the balancebeing iron plus incidential impurities which comprises electricallyapplying to the cast iron to be welded, at welding temperatures, awelding material obtained by simultaneously melting a first and a secondwelding rod; the first welding rod containing, by weight, about 0.085 toabout 0.095 percent carbon, about 0.0285 to about 0.0315 percentchromium, about 0.0095 to about 0.0105 percent nickel, about 0.0095 toabout 0.0105 percent molybdenum, about 0.618 to about 0.672 percentmanganese, about 0.01615 to about 0.01785 percent sulphur, about 0.01805to about 0.01995 phosphorus, about 2.50 percent silicon, with thebalance being iron plus incidential impurities and the first welding rodbeing provided with a low hydrogen fluxing material; the second weldingrod containing, by weight, about 2.85 percent carbon, about 0.01 percentchromium, about 0.10 percent nickel, about 0.05 percent molybdenum,about 0.50 percent manganese, about 0.08 percent sulphur, about 0.50percent phosphorus, about 2.50 percent silicon, with the balance beingiron plus incidential impurities.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

As before noted, the present invention concerns a process for weldingductile cast iron and special welding rods which are used in thisprocess. For the purpose to this invention, ductile iron shall be castiron having the composition set forth in Table 1 below.

                  Table 1                                                         ______________________________________                                        (Cast Ductile Iron Composition)                                               Element          Weight Percent                                               ______________________________________                                        Carbon           3.00 - 4.00                                                  Silicon          1.80 - 2.80                                                  Manganese        0.10 - 1.00                                                  Sulphur          0.00 - 0.03                                                  Phosphorus       0.00 - 0.10                                                                   Bal. Fe, plus                                                                 incidental impurities                                        ______________________________________                                    

In the practice of the invention, in general, welding of the concernedcast iron structure is accomplished as follows:

a. the metal surface is prepared for welding by scarfing it with aselected rod so as to not leave any charred surface,

b. the surface to be welded is scarfed to the proper width in order toinsure that the total welded surface will be penetrated,

c. the selected first welding rod and second welding rod aresimultaneously applied and mixed to the desired degree, and

d. the setting of amperage and voltage on the welding machine aremaintained within the limits recommended for the selected welding rods.

When utilizing the technique of the invention the amount of electriccurrent to be employed is a function of welding rod size. Specifically,with respect to the second welding rod, the electric current to beutilized generally follows the guide lines set forth in Table 2 below.

                  Table 2                                                         ______________________________________                                        Rod Diameter    Amperage                                                      ______________________________________                                        1/4"            About 625 to about 700                                        3/8"            About 725 to about 850                                        1/2"            About 900 to about 1100                                       5/8"            About 1100 to about 1500                                      ______________________________________                                    

The first welding rod contains, by weight, about 0.085 to about 0.095percent carbon, about 0.0285 to about 0.0315 percent chromium, about0.0095 to about 0.0105 percent nickel, about 0.0095 to about 0.0105percent molybdenum, about 0.618 to about 0.672 percent manganese, about0.01615 to about 0.01785 percent sulphur, about 0.01805 to about 0.01995phosphorus, about 2.50 percent silicon, with the balance being iron plusincidential impurities.

The preferred first rod composition is, by weight, about 0.09 percentcarbon, about 0.03 percent chromium, about 0.01 percent nickel, about0.01 percent molybdenum, about 0.64 percent manganese, about 0.017percent sulphur, about 0.019 percent phosphorus, about 2.5 percentsilicon, with the balance being iron plus incidential impurities.

In addition, the first weld rod, i.e., the low hydrogen rod, is providedwith a suitable flux. Such fluxes are well known in the art andtherefore will not be discussed in detail. However, a specific fluxcomposition which has worked exceptionally well includes, by weight,about 43.6 percent calcium carbonate, about 29.2 percent ferric oxide,about 12.5 percent aluminum oxide, about 6.2 percent silicon dioxide,and about 8.5 percent clay. Also, it should be noted with regard to thispreferred fluxing composition, when direct current welding is concernedit is preferred to use a sodium silicate clay whereas when alternatingcurrent welding is involved it is preferred to use a potassium silicateclay.

The flux can be applied to the concerned welding rod in a number ofways. For example, the rod can be grooved or cored and the so-formedcavity filled with the fluxing material. However, it is preferred tosimply coat the concerned welding rod with the desired fluxing material.

In view of the fact that the method manufacture and applying the fluxingmaterial are well known in the art the same shall not be describedherein in detail.

The second welding rod contains by weight, about 2.85 percent carbon,about 0.01 percent chromium, about 0.10 percent nickel, about 0.05percent molybdenum, about 0.50 percent manganese, about 0.08 percentsulphur, about 0.50 percent phosphorus, about 2.50 percent silicon, withthe balance being iron plus incidential impurities.

As the method of producing the alloys utilized to fabricate the firstand second welding rod are well known in the metallurgical art, for thesake of brevity, such techniques will not be discussed herein.

The instant invention has been successfully practiced with numerouswelding rods of the type hereinbefore described. A typical example ofthe practice of the invention is as follows:

EXAMPLE

A specimen of cast iron was selected and surface treated by scarfing.The scarfing was continued to the degree necessary to insure that thetotal surface to be welded would be penetrated. A first welding rod ofthe herein described preferred composition (having a coating of theherein described preferred flux on the surface) was simultaneouslymelted with a second welding rod containing, by weight, about 2.85percent carbon, about 0.01 percent chromium, about 0.10 percent nickel,about 0.05 percent molybdenum, about 0.50 percent manganese, about 0.08percent sulphur, about 0.50 percent phosphorus, about 2.50 percentsilicon, with the balance being iron plus incidential impurities. Thefirst welding rod was about 18 inches in length and had a diameter of1/4 inches. The second welding rod was about 18 inches long with adiameter of 1/2 inches. The welding current ranged from about 1100 toabout 1500 amps.

The resultant weld was then physically inspected and it was determinedthat a continuous, bonded, metallurgically suitable weld had beenobtained.

While there have been described what are at present considered to be thepreferred embodiments of this invention, it will be obvious to thoseskilled in the art that various changes and modifications may be madetherein, without departing from the invention, and it is aimed,therefore, in the appended claims to cover all such changes andmodifications as fall within the true spirit and scope of the invention.

It is claimed:
 1. A process for the electric arc welding of cast ironcomprising:providing a cast iron article to be welded containing, byweight, about 3.00 to about 4.00 percent carbon, about 1.80 to about2.80 percent silicon, about 0.10 to about 1.00 percent manganese, about0.00 to about 0.03 percent sulphur, about 0.00 to about 0.10 percentphosphorus, with the balance being iron plus incidential impurities;electrically applying to the cast iron to be welded, at weldingtemperatures, a welding material obtained by simultaneously melting afirst and second welding rod; said first welding rod containing, byweight, about 0.085 to about 0.095 percent carbon, about 0.0285 to about0.0315 percent chromium, about 0.0095 to about 0.0105 percent nickel,about 0.0095 to about 0.0105 percent molybdenum, about 0.618 to 0.672percent manganese, about 0.01615 to about 0.01785 percent sulphur, about0.01805 to about 0.01995 percent phosphorus, about 2.50 percent silicon,with the balance being iron plus incidential impurities, said firstwelding rod being provided with a low hydrogen fluxing material; saidsecond welding rod containing, by weight, about 2.85 percent carbon,about 0.01 percent chromium, about 0.10 percent nickel, about 0.05percent molybdenum, about 0.50 percent phosphorus, about 0.50 percentmanganese, about 0.08 percent sulphur, about 2.50 percent silicon, withthe balance being iron plus incidential impurites.
 2. The process ofclaim 1 wherein said first welding rod has a coating of fluxing materialthereon consisting essentially of about 43.6 weight percent calciumcarbonate, about 29.2 weight percent ferric oxide, about 12.5 weightpercent aluminum oxide, about 6.2 weight percent silicon dioxide, andabout 8.5 weight percent clay.
 3. The process of claim 2 wherein saidclay is a sodium silicate clay.
 4. The process of claim 2 wherein saidclay is a potassium silicate clay.
 5. The process of claim 1, whereinsaid first welding rod consists essentially of, by weight, about 0.09percent carbon, about 0.03 percent chromium, about 0.01 percent nickel,about 0.01 percent molybdenum, about 0.64 percent manganese, about 0.017percent sulphur, about 0.019 percent phosphorus, about 2.5 percentsilicon, with the balance being iron plus incidential impurities.